/* Alloy Analyzer 4 -- Copyright (c) 2006-2009, Felix Chang
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
 * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package edu.mit.csail.sdg.alloy4;

import java.io.IOException;
import java.net.URL;
import java.time.Instant;
import java.util.Enumeration;
import java.util.jar.Manifest;

/**
 * This holds the buildDate String. The release build script will generate a
 * customized Version.java with the correct buildnumber and date.
 * <p>
 * <b>Thread Safety:</b> Safe.
 */

public final class Version {

	/**
	 * The constructor is private, since this class never needs to be
	 * instantiated.
	 */
	private Version() {}

	public static String	version			= "unknown";
	public static long		buildnumber		= -1;
	public static Instant	builddate		= Instant.ofEpochMilli(0);
	public static String	commit			= "unknown";
	public static boolean	experimental	= true;

	static {
		Manifest manifest = getManifest();
		if (manifest != null) {

			String version = manifest.getMainAttributes().getValue("Bundle-Version");
			if (version != null)
				Version.version = version;

			String commit = manifest.getMainAttributes().getValue("Git-SHA");
			if (commit != null)
				Version.commit = commit;

			String buildnumber = manifest.getMainAttributes().getValue("Bnd-LastModified");
			if (buildnumber != null && buildnumber.matches("\\d+")) {
				Version.buildnumber = Long.parseLong(buildnumber);
				builddate = Instant.ofEpochMilli(Version.buildnumber);
			}
		}

	}

	/**
	 * This is true if this is an experimental version rather than a release
	 * version.
	 */

	/** Returns the build number. */
	public static long buildNumber() {
		return buildnumber;
	}

	/** Returns the version string. */
	public static String version() {
		return version;
	}

	private static Manifest getManifest() {
		try {
			Enumeration<URL> resources = Version.class.getClassLoader().getResources("META-INF/MANIFEST.MF");
			while (resources.hasMoreElements()) {
				URL url = resources.nextElement();
				Manifest m = new Manifest(url.openStream());
				String value = m.getMainAttributes().getValue("Bundle-SymbolicName");
				if (value != null && value.equals("org.alloytools.alloy.dist")) {
					return m;
				}
			}
		} catch (IOException e) {
			// we ignore
		}

		return null;
	}

	/** Returns the build date. */
	public static String buildDate() {
		return builddate.toString();
	}

}